Commonplace, in entertainment media, household appliances, and so forth, haptic devices stimulate a person's sense of touch using physical forces to provide feedback. The word “haptics” comes from a Greek root that roughly translates to “touch.” As such, haptic technology is found in a wide range of applications, from vibrator-chips found in cell phones to da Vinci® surgical systems that enable surgeons to perform incisions remotely while receiving touch feedback.
Haptic devices typically fall into two categories: cutaneous and kinesthetic. Cutaneous haptic devices stimulate the human skin, thereby simulating different textures, temperatures, viscosities, or vibrations. Since the surface of the human skin exhibits extreme sensitivity, cutaneous haptic devices do not need to exert large forces on the surface of the skin to simulate a texture; however, cutaneous haptic devices must be extremely accurate to simulate a virtual texture. An example of a cutaneous haptic device is a Wii™ remote console, an entertainment device that uses a vibration chip to alert a user to certain events. While the vibrations do not replicate textures, they send cutaneous feedback to the user.
A kinesthetic haptic device, on the other hand, simulates a spatial touch environment by exerting forces on, for example, a hand. Kinesthetic haptic devices constitute most of the complex haptic devices available today because such kinesthetic haptic devices typically need to exert a wide range of forces and must be preprogrammed to correctly simulate environments. For instance, a Geomagic® Touch™ haptic device sold by Geomagic, Inc. can simulate a simple linear spring using Hooke's Law to generate forces depending on how far a user pushes a stylus away from a predetermined point.
Haptic devices are used in research facilities to conduct human touch experiments or to develop commercial products such as the da Vinci® surgical systems. However, these haptic devices suffer from the same issue, i.e., their need to be grounded on a nonmoving surface. For example, the Geomagic® Touch™ haptic device sold by Geomagic, Inc. has six degrees of freedom, with an ability to generate a maximum force of 3.3 Newtons in the xyz Cartesian plane. FIG. 1 shows a perspective view of the Geomagic® Touch™ haptic device. As shown in FIG. 1, a mounted base holds a swiveling sphere which, in turn, supports a two stage lever arm tipped with a graspable stylus. FIG. 2 is a diagram illustrating the six (6) degrees of freedom of the haptic device shown in FIG. 1. As indicated in FIG. 2, the six degrees of freedom consist of θ1, θ2, θ3, q2, q3, and the swiveling stylus. In use, a user grips the stylus shown in FIG. 1 and, depending on software, the user will experience a virtual touch environment. However, like many so-called high-grade haptic devices, the Geomagic® Touch™ haptic device must sit securely on an immovable surface to generate any force.
Because such position-sensing haptic devices lack an ability to operate freely in a user's hands without being bound to a surface, typical commercial haptic devices generate forces using methods that include using cellphone vibration chips or watch clickers. Most consumers treat functional haptic features on gadgets such as the Apple Watch as gimmicks rather than helpful features.